Conventionally, an in-vehicle controller (electronic module) mounted on an automobile is typically configured by a circuit board on which an electronic component containing a heating element such as a semiconductor element is mounted, and a casing in which the circuit board is contained. The casing is typically configured by a base to which the circuit board is fixed and a cover to which the base is assembled to cover the circuit board.
In recent years, such an in-vehicle controller tends to be increased in heating amount along as minimization and multifunctionalization are progressed due to space restriction. For example, PTL 1 discloses a technique of a radiation structure through surface treatment on the casing in order that the heat generated in the electronic component (heating element) is transferred to the casing to be radiated from the outer surface of the casing into the atmosphere.
In addition, PTL 2 discloses a heat radiating method in which a coating film is formed in the surface of a radiating member using a coating material containing ceramics particles.